KR20180033289A - Measurement time distribution in reference methods - Google Patents

Abstract

Methods and systems for measuring time distributions (1276, 1277, 1278) for reference schemes are disclosed. The disclosed methods and systems can dynamically change the measurement time distribution based on the sample signal, the reference signal, the noise levels and the SNR. The methods and systems are comprised of a plurality of measurement states including a sample measurement state 1282, a reference measurement state 1284, and a dark measurement state 1286. In some instances, the measurement time distribution scheme may be based on the operating wavelength, the measurement location at the sampling interface, and / or the targeted SNR. Examples of the present disclosure further include systems and methods for simultaneously measuring different measurement conditions. The systems and methods may also include a high frequency detector to remove or reduce correlated noise fluctuations that may reduce the SNR.

Description

Measurement time distribution in reference methods

Cross-reference to related application

The present application claims priority to U.S. Provisional Patent Application No. 62 / 220,887, filed September 18, 2015, which is incorporated by reference in its entirety.

Technical field

The present application relates generally to methods and systems for improving the signal-to-noise ratio for reference schemes, and more particularly to methods and systems for dynamically varying the measurement time distribution and eliminating high- .

Absorption spectroscopy is an analytical technique that can be used to determine the concentration and type of one or more substances in a sample at a sampling interface. Conventional systems and methods for absorption spectroscopy can include emitting light at a sampling interface. When light is transmitted through the sample, some of the light energy may be absorbed at one or more wavelengths. This absorption can result in changes in the properties of light exiting the sample. The properties of the light exiting the sampling interface can be compared to the properties of light exiting the reference and the concentration and type of one or more materials in the sample at the sampling interface can be determined based on this comparison.

The comparison may determine the concentration and type of one or more materials in the sample at the sampling interface, but the measurements may include a fixed measurement time distribution scheme. In some instances, the fixed measurement time distribution scheme may include the same distribution of cycle times for three measurement states, i.e., sample measurement, reference measurement, and dark measurement. However, the sample signal, the reference signal, the dark signal and their corresponding noise levels may differ depending on the operating wavelength, the ambient environment and / or the measurement location of the material in the sample. As a result, the fixed measurement time distribution scheme may not be optimal for all operating wavelengths and measurement locations in the sample. In addition, fixed measurement time distribution schemes can result in long measurement times with non-critical information, erroneous measurement data, a low signal-to-noise ratio (SNR), or a combination thereof. Accordingly, methods and systems for dynamically changing the measurement time distribution may be required. In addition, high frequency noise in the system may result in unacceptable SNR, so that methods and systems for eliminating high frequency noise may be required.

This relates to the measurement time distribution for the reference schemes. The disclosed methods and systems can dynamically change the measurement time distribution based on the sample signal, the reference signal, the noise levels and the SNR. The methods and systems may comprise a plurality of measurement states including a sample measurement state, a reference measurement state, and a dark measurement state. In some instances, less time may be allocated to the dark measurement state if the noise levels of the system are low. In some instances, the sample signal may be weak and the system may allocate a larger amount of time to the sample measurement state than other measurement states. In some instances, the sample signal may be strong, and the system may allocate a larger amount of time to the reference measurement state than other measurement states. In some instances, the measurement time distribution scheme may be based on the operating wavelength, the measurement location in the sample and / or the targeted SNR. Examples of the present disclosure further include systems and methods for simultaneously measuring different measurement conditions. The systems and methods may also include a high frequency detector to remove or reduce correlated noise fluctuations that may reduce the SNR.

FIG. 1 illustrates an exemplary system including a plurality of detectors for measuring the concentration and type of one or more materials in a sample in accordance with the examples of this disclosure.
Figure 2 illustrates an exemplary process flow for measuring the concentration and type of one or more materials in a sample using a system comprising a plurality of detectors in accordance with the examples of this disclosure.
Figure 3 illustrates an exemplary system including a shared detector for measuring the concentration and type of one or more materials in a sample in accordance with the examples of this disclosure.
Figure 4 illustrates an exemplary process flow for measuring the concentration and type of one or more materials in a sample using a system including a shared detector according to the examples of this disclosure.
Figure 5 illustrates an exemplary plot of absorbance measurements for determining the concentration and type of one or more materials in accordance with the examples of this disclosure.
Figure 6 illustrates an exemplary system including a modulator positioned between a light source and a sample to measure the concentration and type of one or more materials in the sample in accordance with the examples of this disclosure.
Figure 7 illustrates an exemplary process flow for measuring the concentration and type of one or more materials in a sample using a system including a modulator positioned between the light source and the sample in accordance with the examples of this disclosure.
Figure 8 illustrates an exemplary system including a modulator positioned between a light source and a sample to measure the concentration and type of one or more materials in the sample in accordance with the examples of this disclosure.
9 illustrates an exemplary process flow for measuring the concentration and type of one or more materials in a sample using a system including a modulator located between a light source and a sample in accordance with the examples of the present disclosure.
Figure 10 illustrates an exemplary plot of absorbance measurements used to determine the concentration and type of one or more substances in accordance with the examples of this disclosure.
Figure 11 shows an exemplary plot of absorbance measurements involving three measurement states with the same measurement time distribution in accordance with the examples of this disclosure.
Figure 12 shows an exemplary plot of absorbance measurements involving three measurement states with unequal measurement time distributions in accordance with the examples of this disclosure.
Figure 13 illustrates an exemplary process flow for dynamically varying the measurement time distribution in accordance with the examples of this disclosure.
Figure 14 illustrates a portion of an exemplary system capable of measuring the concentration and type of one or more materials in a sample and measuring different measurement states simultaneously in accordance with the examples of this disclosure.
Figure 15 illustrates an exemplary plot of measurement states for a system that can measure different measurement states simultaneously according to the examples of this disclosure.
16 illustrates a cross-sectional view of a portion of an exemplary system that includes a plurality of MEMS components and can measure different measurement states simultaneously according to examples of the present disclosure.
Figure 17 shows an exemplary plot of absorbance measurements with noise variations in accordance with the examples of this disclosure.
Figure 18 illustrates an exemplary system for measuring the concentration and type of one or more materials in a sample comprising a high frequency detector in accordance with the examples of this disclosure.
Figure 19 illustrates an exemplary process flow for measuring the concentration and type of one or more materials in a sample using a system including a high frequency detector in accordance with the examples of this disclosure.

In the following description of examples, reference is made to the accompanying drawings, and specific examples that may be practiced are shown by way of illustration in the drawings. It should be understood that other examples may be utilized and structural changes may be made without departing from the scope of the various examples.

Representative applications of methods and devices in accordance with the present disclosure are described in this section. These examples are provided merely to add context and to aid understanding of the examples described. Accordingly, it will be apparent to those skilled in the art that the described examples can be practiced without some or all of the specific details. Other applications are possible and, therefore, should not be construed as limiting the following examples.

Various techniques and process flow steps will be described in detail with reference to examples shown in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects and / or features described or mentioned herein. It will be apparent, however, to one of ordinary skill in the art that one or more aspects and / or features described or mentioned herein may be practiced without some or all of these specific details. In other instances, well-known process steps and / or structures have not been described in detail so as not to obscure aspects and / or features described or implied herein.

Also, although process steps or method steps may be described in a sequential order, such processes and methods may be configured to operate in any suitable order. In other words, any sequence or order of steps that may be described in this disclosure does not by itself indicate a requirement that the steps be performed in that order. In addition, some steps may be performed concurrently, even though they are described or implied as occurring asynchronously (e.g., because one step is described after another step). It should also be understood that the process illustrated by way of example in the drawings does not imply that the illustrated process excludes other variations and modifications thereto, and that the illustrated process or any of its steps may be implemented in one or more of the examples It does not imply that it is necessary, nor does it imply that the illustrated process is preferred.

This disclosure relates to measurement time distributions for reference schemes. The disclosed methods and systems can dynamically change the measurement time distribution based on a sample signal, a reference signal, a dark signal, noise levels, SNR, or a combination thereof. The methods and systems may comprise a plurality of measurement states including a sample measurement state, a reference measurement state, and a dark measurement state. In some instances, less time may be allocated to the dark measurement state if the noise levels of the system are low. In some instances, the sample signal may be weak and the system may allocate a larger amount of time to the sample measurement state than other measurement states. In some instances, the sample signal may be strong, and the system may allocate a larger amount of time to the reference measurement state than other measurement states. In some instances, the amount of time assigned to the sample measurement state and the reference measurement state may be based on the noise level. In some instances, the noise level may depend on the strength of the sample signal, the reference signal, or both. In some instances, the measurement time distribution scheme may be based on the operating wavelength, the measurement location in the sample, the ambient conditions, and / or the targeted SNR. Examples of the present disclosure may further include systems and methods for simultaneously measuring different measurement conditions. In addition, the systems and methods may include a high frequency detector to remove or reduce time-correlated noise fluctuations that may reduce the SNR in certain reference schemes.

For materials in a sample, each material may have a signature in a particular wavelength system represented by a pattern as a function of the wavelength formed by the one or more absorbance peaks. One exemplary wavelength scheme may be short wavelength infrared (SWIR). A material can absorb a greater amount of energy at one or more wavelengths and absorb a lesser amount of energy at other wavelengths to form a spectral fingerprint that is unique to the material. Determination of the type of one or more materials in the sample may be performed by matching the measured spectrum with the contents of a spectral library comprising fingerprints of related materials. Additionally, the concentration of the substance may be based on the amount of absorption.

The sample may include a plurality of materials capable of modifying incident light. Of the plurality of materials, one or more materials may be of interest, and other materials may not be of interest. In some instances, materials that are not of interest can absorb more incident light than materials of interest. Additionally, spectral artifacts may "mask" the absorbance peaks of one or more substances of interest. Both absorption of spectral artifacts and non-interest materials can make detection of the substance of interest difficult. In addition, the concentration of one or more substances can be distributed in a non-uniform manner in the sample, which can produce changes in the optical properties of the sample (e.g., linear birefringence, optical activity, diattenuation) . Changes in optical properties in the sample may result in different signal values based on the measurement position in the sample. Additionally, the absorbance of materials not of interest or the noise levels at different locations within the sample may be different. In addition, components of the system may have different drifts over time, which may change signal values and / or noise levels. Different signal values and / or different noise levels may result in varying SNRs based on some factors, e.g., wavelength, measurement location in the sample, or both.

Absorption spectroscopy is an analytical technique that can be used to determine the concentration and type of one or more substances in a sample. The light may have an initial intensity or energy when it is emitted from the light source and incident on the sample. When light is transmitted through the sample, some of the energy can be absorbed at one or more wavelengths. This absorption may result in a change in the intensity of the light exiting the sample (e. G., Loss). As the concentration of the material in the sample increases, a greater amount of energy can be absorbed, which can be represented by the following Beer-Lambert Law:

(1)

(One)

Where l may be the path length of the light through the sample, c may be the concentration of the substance of interest, and T may be the transmittance of light exiting the sample , I _sample may be the intensity along the sample path measured at the measurement wavelength, and I _reference may be the intensity along the reference path measured at the measurement wavelength.

As shown in Equation 1, the amount of light exiting the sample can be an exponential function of the concentration. Given a relationship between the absorbance and the permeability measurement mentioned in Equation 1, there may be a linear relationship between the absorbance of the material in the sample and the concentration. In some instances, the concentration of the substance may be determined based on the absorbance measurement. In some instances, the reference path may comprise a reference "sample" having a known concentration of one or more substances of interest. In some instances, the concentration of a substance in a sample can be calculated using a criterion and a proportional equation defined as: < RTI ID = 0.0 >

(2)

(2)

Where A _sample and A _reference are the sample absorbance and the reference absorbance, respectively, and C _sample and C _reference are the concentrations of the substance in and within the sample, respectively. In some instances, a material may comprise one or more chemical components, and the measurement may be used to determine the concentration of each chemical component present in the sample.

Figure 1 illustrates an exemplary system, and Figure 2 illustrates an exemplary process flow for measuring the concentration and type of one or more materials in a sample using a system comprising a plurality of detectors in accordance with the examples of this disclosure . The system 100 may include a light source 102 that is controlled by the controller 140 via a signal 104. Light source 102 may emit multi-band or multi-wavelength light 150 toward monochromatic light 106 (step 202 of process 200). A monochromator is a component that can select one or more discrete wavelengths from multi-wavelength light 150. In some instances, the one or more discrete wavelengths may include a limited range of wavelengths. In some instances, the monochromatic photon 106 may include an entrance slit configured to select and / or select a spectral resolution, or to exclude unwanted light or stray light. The monochromator may be coupled with one or more interference or absorptive filters, prisms, or diffraction gratings for wavelength selection. Monochromatic photon 106 can split light 150 into one or more discrete wavelengths to form light 152 (step 204 of process 200). The light 152 may be incident on the beam splitter 110. A beam splitter is an optical component that can separate a beam of light into a plurality of beams of light. Beam splitter 110 can separate light 152 into two light beams, light 154 and light 164 (step 206 of process 200).

The light 154 may be incident on the sample 120. A portion of the light can be absorbed by the material in the sample 120 and a portion of the light can be transmitted through the sample 120 (step 208 of process 200). In some instances, a portion of the light may be scattered. Scattering can result in optical loss and change the path length of the light transmitted through the sample 120. A portion of the light transmitted through the sample 120 may be represented by light 156. The light 156 may comprise a set of photons that may impinge on the active area of the detector 130. The detector 130 can respond to or measure light or photons that impinge on the active area (step 210 of the process 200), generate an electrical signal 158 that can display the properties of the light 156 (Step 212 of process 200). The electrical signal 158 may be input to the controller 140.

Light 164 may be directed towards mirror 112 (step 214 of process 200). Mirror 112 may be any type of optical device capable of directing or redirecting light toward reference 122. In some instances, the system may additionally or alternatively include non-reflective component (s) (e.g., a curved waveguide) for light redirection, but is not limited thereto. In some instances, the system 100 may include other types of optical devices, such as light guides, diffraction gratings, or reflectors. The light 164 may be incident on the reference 122. A portion of the light 164 may be absorbed by the material within the reference 122 and a portion of the light 164 may be transmitted through the reference 122 as the light 166 216). The light 166 may comprise a set of photons that may be incident on the detector 132. In some instances, detector 130 and detector 132 may be matched detectors. That is, detector 130 and detector 132 may have similar characteristics, including, but not limited to, the type of detector, operating conditions, responsiveness, and performance. The detector 132 can respond to or measure light or photons that impinge on the active area (step 218 of process 200) and generate an electrical signal 168 indicative of the properties of light 166 (Step 220 of process 200). The electrical signal 168 may be input to the controller 140.

Controller 140 may receive both signal 158 and signal 168. In some instances, signal 158 may comprise a sample signal and signal 168 may comprise a reference signal. The controller 140 may divide, subtract, or scale the sample signal to a reference signal, for example, to obtain a ratio. The ratio can be converted to absorbance by using Equation 1, and an algorithm for determining the concentration of the substance can be applied to the absorbance spectrum.

One benefit of using the system 100 (shown in FIG. 1) to determine the composition of the materials in the sample is the ability to determine variations, drifts, and / or variations that result from light sources that are not caused by changes in the composition of the material Changes can be compensated for. For example, if the characteristics of light 152 emitted from light source 102 change unexpectedly, both light 154 and light 164 may equally be affected by this unexpected change. As a result, both light 156 and light 166 can be equally affected so that when controller 140 divides, scales, or subtracts signal 158 to signal 168, The change can be removed or proportionally eliminated. However, because system 100 includes two different detectors (e.g., detector 130 and detector 132) for absorbance measurements, variations, drift and / or changes resulting from the detectors themselves May not be compensated. Although the detector 130 and the detector 132 may be matched (i.e., have the same characteristics), the rate or effect that various factors unrelated to the material, such as environmental conditions, may have for the different detectors may not be the same . Those skilled in the art will appreciate that the same features may include tolerances that result in a 15% deviation. Due to the different effects on the different detectors, only one signal, not both signals, can be disturbed. Instead of recognizing that there is a factor that is independent of the material from which the controller 140 has disturbed only one signal, the controller 140 determines the difference in the concentration of the sample 120 compared to the reference 122, Disturbances can be miscalculated. Alternatively or additionally, the controller 140 may mislead the type of material if the disturbance results in a change in the spectral fingerprint.

There can be many causes of variations, drift and changes. One exemplary drift may be an initialization drift due to "warming up" of components. The user may wait for a certain amount of time until such initialization drift is stabilized, but this may not be a suitable solution in certain applications. For example, in systems requiring low power consumption, certain components may be turned off to conserve power when not in use, and switched on if used. Waiting for the components to warm up can exhaust the user depending on how long it takes to stabilize. Also, the power consumed during standby can nullify the advantage of turning off the components.

Other exemplary drifts may be due to noise. For example, there may be a 1 / f noise due to random changes in the resistivity contacts of the electrodes and / or effects from the indicative measurement state traps in the component. Due to random changes, the changes can affect not only the unpredictability but also the different detectors in different ways. Other exemplary drifts can be thermally drifted due to changes in the temperature and / or humidity of the ambient environment, which can also affect different detectors in different ways.

Regardless of the source of fluctuations, drift, and changes, the effect that the one detector causes the sample to measure and the different detector to measure the reference can result in unwanted changes in sensitivity, sensitivity, and / or absorbance spectrum. Because the optical path traveling through the sample may be different from the optical path traveling through the reference and there may be many unshared components or unmapped correlations between the two paths, May be indistinguishable from changes in the signal due to the material of interest.

Since the light source 102 in the system 100 can be shared, the drift and instabilities attributable to the light source 102 can be compensated. However, drift or instabilities due to components that are not shared (i.e., not common) along both optical paths may not be compensated. Also, the measurement capabilities of the system may be limited in situations where detectors are limited to shot noise. Shot noise is the noise or current generated from the random generation and flow of mobile charge carriers. For shot noise limited detectors, different detectors may have random and / or different noise floors. As a result, the system 100 (shown in FIG. 1) may not be suitable for high sensitivity or low signal measurements.

Figure 3 illustrates an exemplary system, and Figure 4 illustrates an exemplary process flow for measuring the concentration and type of one or more materials in a sample using a system including a shared detector in accordance with the examples of this disclosure . The system 300 may include a light source 302 controlled by a controller 340 via a signal 304. Light source 302 may emit multi-wavelength light 350 toward monochromatic light 306 (step 402 of process 400). Monochromator 306 may split multi-wavelength light 350 into one or more discrete wavelengths of light including light 352 (step 404 of process 400). Light 352 may be directed toward beam splitter 310 and then beam splitter 310 may split the light into two light beams, i.e., light 354 and light 364 (Step 406 of process 400).

Light 354 may be incident on sample 320. A portion of the light may be absorbed by the material in the sample 320 and a portion of the light may be transmitted through the sample 320 (step 408 of the process 400). A portion of the light transmitted through the sample may be referred to as light 356. [ Light 356 may be directed towards mirror 314. Mirror 314 may direct or change the propagation direction of light 356 toward selector 324 (step 410 of process 400).

Light 364 may be incident on mirror 312. Mirror 312 may change the propagation direction of light toward reference 322 (step 412 of process 400). A portion of the light 364 may be absorbed by the chemical material within the reference 322 and a portion of the light 364 may be transmitted through the reference 322 (step 414 of the process 400). A portion of the light transmitted through the reference 322 may be referred to as light 366.

Both light 356 and 366 may be incident on selector 324. The selector 324 may be any optical component capable of moving or selecting the light beam to direct it towards the chopper 334. [ The chopper 334 may be a component that periodically interrupts the light beam. The system 300 can alternate in time between chopper 334 modulating light 356 and modulating light 366. [ The light transmitted through the chopper 334 may be incident on the active area of the detector 330. Both light 356 and light 366 may comprise a set of photons incident on detector 330, respectively. The detector 330 may correspond to or measure incident light or photons and may generate an electrical signal indicative of the properties of the light.

At a first time, chopper 334 may modulate light 356 (step 416 of process 400). The detector 330 may measure the transmitted light 356 through the sample 320 (step 418 of the process 400) and generate an electrical signal 358 indicative of the properties of the light 356 (Step 420 of process 400). At a second time, chopper 334 may modulate light 366 (step 422 of process 400). The detector 330 may measure the transmitted light 366 through the reference 322 (step 424 of the process 400) and generate an electrical signal 368 indicative of the properties of the light 366 (Step 426 of process 400).

Controller 340 may receive both signal 358 and signal 368 at different times. Signal 358 may comprise a sample signal, and signal 368 may comprise a reference signal. The controller 340 may divide, subtract, or scale the sample signal to a reference signal, for example, to obtain a ratio (step 428 of process 400). The ratio can be converted to absorbance by using Equation 1, and an algorithm for determining the concentration of the substance can be applied to the absorbance spectrum.

Although system 300 (shown in FIG. 3) can compensate for minor variations, drifts, and / or changes in the detector due to the shared detector, it is clear that system 300 identifies between different types of drift It can be difficult. There can be many types of drifts, such as zero drift and gain drift. Zero drift can refer to a change in the zero level with time, thereby avoiding a constant (i.e., horizontal) relationship over time. Gain drift can refer to a change in the average number of electron carriers per generated electron-hole pair. That is, the gain drift can refer to a change in efficiency or ratio to the current response of the detector of generated electron-hole pairs. To distinguish between zero drift and gain drift, the system can stabilize one type of drift and measure another type of drift. For example, to determine the gain drift from the light source, the system may be DC stabilized (i.e., stable zero drift). However, due to the lack of ability to stabilize one type of drift in system 300, zero drift and gain drift may not be identified.

In some instances, the presence of stray light can be measured by the detector, which can lead to erroneous determination of the erroneous signal and the concentration and type of one or more substances. The placement of the chopper 334 after the light is transmitted through the sample 320 or reference 322 may result in stray light reaching the sample 320 or reference 322. [ The stray light may not contribute to the spectroscopic signal so that by allowing stray light to reach the sample 320 or reference 322, the detector 330 can detect photons contained in the stray light. Detecting the photons contained in the stray light may result in erroneous changes in either signal 358 or signal 368. In response to a change in signal 358 or signal 368, controller 340 may not be able to determine whether this change is due to stray light or due to changes in light source 302 or how much . Thus, the system 300 may not be suitable for situations in which a negligible amount of stray light may be present.

When a substance of interest in the sample has a low concentration, a system with increased accuracy and sensitivity is required compared to the system 100 (shown in FIG. 1) and the system 300 (shown in FIG. 3) . To measure the concentration and type of one or more materials, the system 100 (shown in FIG. 1) and the system 300 (shown in FIG. 3) can measure the sample and the reference multiple times. Figure 5 illustrates an exemplary plot of absorbance measurements for determining the concentration and type of one or more materials in accordance with the examples of this disclosure. The system may begin with a dark phase 570, where one or more components of the system may be optimized, calibrated, and / or synchronized to minimize errors. The dark phase 570 may include, for example, measuring the reference absorbance. In some instances, the dark phase 570 may include measuring the dark current and noise of the system. A sample having a known and stable concentration of material can be placed in the optical path in which the sample is located. The system may be either on or off. The controller can determine the absorbance and set the same "zero level" as this absorbance. If the signal is saturated or clipped due to significant drift, the controller can adjust the light emission properties until the signal is no longer saturated.

Once the dark phase 570 is complete and the zero level is determined, the system may proceed to the measurement phase 572. [ At measurement phase 572, the concentration of material in the sample may be measured by multiple sampling to produce a plurality of sample points 574. In some instances, the system may measure from tens to hundreds of sample points 574. Once a certain number of sample points 574 have been measured, the controller can average the values of sample points 574 to determine the absorbance. As shown in the figure, absorbance measurements may be required to measure and average a number of sample points, since they may include minor perturbations that, if not considered, can result in errors in the determination of the concentration of the substance have. In some instances, when the light source changes the emission wavelength, the dark phase 570 returns to the zero level after a predetermined time has elapsed between successive dark phases, or after a predetermined number of sample points have been measured It can be repeated to zero.

In some instances, the measurement procedure shown in FIG. 5 may have long times between consecutive dark phases, resulting in an incorrect average signal measurement due to the set zero level drifting from the actual zero level. The figure shows zero drift or gain drift where the absorbance signal can begin to deviate from a constant (i.e., horizontal) relationship over time due to the zero level or the gain value drifting away from the actual zero level or actual gain value, respectively have. The time between consecutive dark phases can be shortened, but there may be a limitation on the minimum time period between dark phases due to the minimum number of sample points that may be required for accurate measurement. This may be particularly true in low SNR situations, which may require tens to hundreds of repeated measurements to achieve a somewhat accurate average absorbance value.

FIG. 6 illustrates an exemplary system, and FIG. 7 illustrates an exemplary system for measuring the concentration and type of one or more materials in a sample using a system including a modulator positioned between a light source and a sample, Process flow. The system 600 may include a light source 602 coupled to the controller 640. Controller 640 may send signal 604 to light source 602. In some instances, the signal 604 may comprise a current or voltage waveform. The light source 602 may be oriented toward the filter 606 and the signal 604 may cause the light source 602 to emit the light 650 towards the filter 606 702). Light source 602 may be any super-continuum source, including lamps, lasers, light emitting diodes (LEDs), organic LEDs (OLEDs), electroluminescent (EL) sources, super-light emitting diodes, fiber- Including but not limited to, any combination of one or more of the above. In some instances, the light source 602 may emit a single wavelength of light. In some instances, the light source 602 may emit a plurality of wavelengths of light. In some instances, the plurality of wavelengths may be adjacent to each other to provide a continuous output band. In some instances, light source 602 may be a super-continuum source capable of emitting light in at least a portion of both the SWIR and MWIR ranges. The super-continuum source may be any broadband light source that outputs a plurality of wavelengths. In some instances, the light source 602 may be any tunable source capable of generating SWIR signatures.

The filter 606 may be any type of filter capable of tuning or selecting a single wavelength or a number of discrete wavelengths by tuning the drive frequency. In some instances, the filter 606 may be an acousto-optically tunable filter (AOTF). In some instances, the filter 606 may be an angular tunable narrow band pass filter. Although not shown in the figures, the filter 606 may be coupled to the controller 640 and the controller 640 may tune the drive frequency of the filter 606. In some instances, the filter 606 may be a passband filter configured to selectively permit one or more successive bands of light (i.e., wavelength ranges) to be transmitted. The light 650 may comprise a plurality of wavelengths (step 702 of the process 700), transmitted through the filter 606, and then formed into a light 652 comprising one or more discrete wavelengths (Step 704 of process 700). In some instances, light 652 may include light of less wavelengths than light 650. Light 652 may be directed towards beam splitter 610. The beam splitter 610 may be any type of optical device capable of separating the incident light into a plurality of light beams. In some instances, each light beam separated by beam splitter 610 may have the same optical properties. It will be appreciated by those of ordinary skill in the art that the same optical properties may include tolerances that cause a 15% deviation. Beam splitter 610 may split light 652 into two light beams, light 654 and light 664 (step 706 of process 700), as shown in the figure. .

Light 654 may be transmitted through chopper 634 where chopper 634 may modulate the intensity of light 654 (step 708 of process 700). Chopper 634 may be any component capable of modulating an incident light beam. In some instances, chopper 634 may be an optical chopper. In some instances, chopper 634 may be a mechanical shutter. In some instances, the chopper 634 may be a modulator or a switch. Light 654 may be transmitted through optical device 616 (step 710 of process 700). The optical device 616 may include one or more components configured to change behaviors and properties, such as the beam spot size and / or angle of propagation of the light 654. The optical device 616 may include, but is not limited to, a lens or lens array, a beam-directing element, a collimating or focusing element, a diffractive optics, a prism, a filter, a diffuser, and a light guide. The optical device 616 may include any optical system suitable for measuring the concentration and type of one or more materials within the sample 620 in a resolved path sampling (RPS) system, confocal system, As shown in FIG. The optical device may be an optical system capable of resolving a plurality of incident angles on the sample interface and different path lengths contained in the plurality of optical paths. In some examples, the optical system includes one or more incident light beams having an incident angle in the range of path lengths and angles within a range of path lengths, and an optical system having an incident angle outside the range of path lengths and angles outside the range of path lengths, And reject paths.

Light 654 may be transmitted through sample 620. Energy may be absorbed at one or more wavelengths by the material within the sample 620, resulting in a change in properties of the light 656 exiting the sample (step 712 of process 700). In some instances, light 656 may be formed by reflection or scattering of the material located within the sample. Light 656 may be incident on mirror 614 and mirror 614 may direct or redirect light 656 toward selector 624 (step 714 of process 700). Mirror 614 can be any type of optical device that can change the direction or angle of propagation of light. For example, the mirror 614 may be a concave mirror configured to change the light propagating direction by 90 degrees. In some instances, the system may additionally or alternatively include non-reflective component (s) (e.g., a curved waveguide) for light redirection, but is not limited thereto.

Light 664 may be incident on mirror 612 (step 716 of process 700). Mirror 612 may redirect light 664 toward detector 630. [ Mirror 612 can be any mirror that can change the direction or angle of propagation of light. In some instances, the system may additionally or alternatively include non-reflective component (s) (e.g., a curved waveguide) for light redirection, but is not limited thereto. In some instances, the mirror 612 may have the same optical properties as the mirror 614. Light 664 can be transmitted through a chopper 636 that can modulate the intensity of light 664 (step 718 of process 700). In some instances, chopper 634 and chopper 636 may have identical chopper characteristics, such as chopping frequency and disk configuration. Those skilled in the art will appreciate that the same chopper characteristics may include tolerances that result in a 15% deviation. In some instances, the chopper 636 may be a shutter, such as a micro electro mechanical system (MEMS) shutter. In some instances, the chopper 636 may be a modulator or a switch. The modulated light may be transmitted through filter 608 to produce light 666 (step 720 of process 700). The filter 608 may be any type of filter capable of selectively transmitting light. In some instances, the filter 608 may be a neutral density filter, a blank attenuator, or a filter configured to attenuate or reduce the intensity of all wavelengths of light. In some instances, the filter 608 may attenuate light by a predetermined or known constant value or an attenuation factor.

Both light 656 and light 666 may be incident on selector 624. The selector 624 may be any optical component that can move or select the light beam to be directed toward the detector 630. [ System 600 may alternate in time between allowing light 656 to be incident on detector 630 at one time and allowing light 666 to be incident on detector 630 at another time . In both situations, light 656 and light 666 may each comprise a set of photons. The photons can be incident on the detector 630 and the detector 630 can generate an electrical signal indicative of the properties of the incident light or the number of conflicting photons. The detector 630 may measure a set of photons from light 656 (step 722 of process 700) and generate an electrical signal 658 (step 724 of process 700) ). Signal 658 may represent properties of light 656 that may represent energy from light 654 returned by the material of interest in sample 620. [ Detector 630 may measure a set of incident photons from light 666 (step 726 of process 700) and generate an electrical signal 668 (step 728 of process 700) )). Signal 668 may represent attributes of light 664 not absorbed by filter 608 and may act as a reference signal.

Detector 630 may be any type of photodiode, photoconductors, bolometers, pyrotechnic detectors, charge coupled devices (CCDs), thermocouples, thermistors, photocells and photomultipliers such as photomultiplier tubes, that can measure or respond to light or photons. Detector 630 may comprise a single detector pixel or detector array, such as a multi-band detector or a focal plane array (FPA). The detector array may include one or more detector pixels disposed on the substrate. The detector pixel may comprise one or more detector elements having a common footprint. The detector element may be an element designed to detect the presence of light and may separately generate a signal indicative of the detected light. In some instances, the detector 630 may be any type of detector capable of detecting light in the SWIR. Exemplary SWIR detectors can include, but are not limited to, mercury cadmium telluride (HgCdTe), indium antimonide (InSb), and indium gallium arsenide (InGaAs). In some instances, the detector 630 may be an SWIR detector capable of operating in the extended wavelength range (up to 2.7 [mu] m).

Controller 640 may receive both signal 658 and signal 668, where each signal may be received at a different time. Signal 658 may comprise a sample signal, and signal 668 may comprise a reference signal. The controller 640 may divide, subtract, or scale the sample signal to a reference signal to obtain, for example, the ratio (step 730 of process 700). The ratio can be converted to absorbance by using Equation 1, and an algorithm for determining the concentration of the substance can be applied to the absorbance spectrum. In some instances, the controller 640 may compare the reference absorbance to one or more absorbance values stored in a look-up table or memory to determine the concentration and type of one or more substances in the sample. Although Equation 2 and the discussion above are provided in the context of absorbance, examples of the present disclosure include, but are not limited to, any optical properties such as reflectance, refractive index, density, concentration, scattering coefficient and scattering anisotropy.

The system 600 may be an alternative to the system 100 (shown in Fig. 1) and the system 300 (shown in Fig. 3). System 600 may have a shared detector (e.g., detector 630) for measuring light through sample 620 and (arbitrary) filter 608. Utilizing a shared detector can eliminate or mitigate unpredictable changes in sensitivity, sensitivity and / or absorbance due to different (or random) variations, drifts, and / or changes. As discussed above, fluctuations, drifts, and / or changes may be due to initialization, 1 / f noise, and / or environmental changes that may affect the two detectors in different ways. In addition, the system 600 may tolerate and discard non-negligible amounts of stray light due to the placement of the chopper 634 and the chopper 636 in the optical path before being incident on the sample 620 and the filter 608, respectively . In addition, unlike system 100 and system 300, system 600 may take into account any variations, drifts, and / or changes that result from both light source 602 and detector 630.

In some instances, the attenuation of the incident light by the filter 608 by a predetermined or known constant value causes the light 656 (i.e., the light transmitted through the sample 620) and the light 666 608) of the light-emitting device. This mismatch may be due to different absorbances at different wavelengths. At one or more wavelengths, the material in the sample 620 may absorb a large percentage of light, and thus a low attenuation factor for the filter 608 may be appropriate at such one or more wavelengths. At other wavelengths, the same material in the sample 620 and the same concentration of that material may absorb very little light, and therefore a high attenuation factor for the filter 608 would be appropriate. Since the filter 608 can attenuate by a constant value for all wavelengths of interest, the exact measurements of the system 600 can be limited to only one or a small number of wavelengths. Also, if the attenuation factor is not optimal, a blank attenuator or neutral density filter may not be effective when detecting a low concentration of the substance of interest in the sample. Thus, it may be desirable to consider a change in absorbance for the wavelength in the sample 620 and to be able to detect a low concentration of material in the sample.

FIG. 8 illustrates an exemplary system, and FIG. 9 illustrates a method of measuring the concentration and type of one or more materials in a sample at a sampling interface using a system including a modulator located between the light source and the sample, ≪ / RTI > FIG. The system 800 may include a light source 802 coupled to the controller 840. Controller 840 may send signal 804 to light source 802. [ In some instances, the signal 804 may comprise a current or voltage waveform. The light source 802 may be oriented toward the filter 806 and the signal 804 may cause the light source 802 to emit light 850 (step 902 of process 900). Light source 802 may be any source capable of emitting light 850. In some instances, the light source 802 may emit a single wavelength of light. In some instances, the light source 802 may emit a plurality of wavelengths of light. Exemplary light sources may include, but are not limited to, lamps, lasers, LEDs, OLEDs, EL sources, super-light emitting diodes, super-continuous sources, fiber-based sources or combinations of one or more of these sources. In some examples, the plurality of wavelengths may provide a continuous output band close to or adjacent to each other. In some instances, the light source 802 may be any tunable source capable of generating SWIR signatures. In some instances, the light source 802 may be a super-continuum capable of emitting light in at least a portion of both SWIR and MWIR.

The filter 806 may be any filter capable of tuning and selecting a single wavelength or multiple discrete wavelengths by tuning the drive frequency. In some instances, the filter 806 may be an AOTF. In some instances, the filter 606 may be an angular tunable narrow band pass filter. Although not shown in the figures, the filter 806 may be coupled to the controller 840, and the controller 840 may tune the driving frequency of the filter 806. [ In some instances, the filter 806 may be a transmission band filter configured to selectively allow one or more continuous bands of light (i.e., wavelength ranges) to be transmitted. Light 850 may comprise a plurality of wavelengths and may be transmitted through filter 806 and then form light 852 comprising one or more discrete wavelengths (step 904 of process 900). )). In some instances, light 852 includes light of less wavelengths than light 850. Light 852 may be directed towards beam splitter 810. The beam splitter 810 may be any type of optical device capable of separating the incident light into a plurality of light beams. In some instances, each light beam separated by beam splitter 810 may have the same optical properties. It will be appreciated by those of ordinary skill in the art that the same optical properties may include tolerances that cause a 15% deviation. As shown in the figure, beam splitter 810 may split light 852 into two light beams, light 854 and light 864 (step 906 of process 900) .

Light 854 can be transmitted through chopper 834 where chopper 834 can modulate the intensity of light 854 (step 908 of process 900). The chopper 834 may be any component capable of modulating or periodically interrupting an incident light beam. In some instances, chopper 834 may be an optical chopper. In some instances, chopper 834 may be a mechanical shutter, such as a MEMS shutter. In some instances, the chopper 834 may be a modulator or a switch. Light 854 may be transmitted through optical device 816 (step 910 of process 900). The optical device 816 may include one or more components configured to alter the behavior and properties of light, such as the beam spot size of the light 854 and / or the angle of propagation. The optical device 816 may include, but is not limited to, a lens or lens array, a beam-directing element, a collimating or focusing element, a diffractive optics, a prism, a filter, a diffuser, and a light guide. The optical device 816 may include any type of optical system, such as an RPS system, confocal system, or any optical system suitable for measuring the concentration and type of one or more materials within the sample 820. [

The light 854 may be directed toward the sample 820. Sample 820 may absorb a portion of light 854 and a portion of light 854 may be transmitted at one or more wavelengths (step 912 of process 900). A portion of the light 854 may be absorbed by the material in the sample 820 and a portion of the light 854 may be transmitted through the sample 820. [ A portion of the light 854 transmitted through the sample 820 may be referred to as light 856. In some instances, light 856 may be formed by reflection or scattering of the material located within the sample 820. Light 856 may be directed toward mirror 814 and mirror 814 may direct light 856 toward mirror 814 (step 914 of process 900). Mirror 814 can be any type of optical device that can change the direction of light propagation. In some instances, the mirror 814 may be a concave mirror configured to change the light propagation direction by 90 degrees. In some instances, the system may additionally or alternatively include non-reflective component (s) (e.g., a curved waveguide) for light redirection, but is not limited thereto.

The second optical path formed by beam splitter 810 that separates light 852 may be referred to as light 864. The light 864 may be directed towards the mirror 812. Mirror 812 can be any type of optical device that can change the direction of propagation of light 864. Mirror 812 may direct or redirect light 864 toward selector 824 (step 916 of process 900). Light 864 may be transmitted through chopper 836 and chopper 836 may modulate light 864 (step 918 of process 900). The chopper 836 may be any component capable of modulating the intensity of the incident light beam. In some instances, chopper 834 and chopper 836 may have the same chopping characteristics, such as chopping frequency and disk configuration. Those skilled in the art will appreciate that the same chopping characteristics may include tolerances that result in a 15% deviation. In some instances, chopper 836 may be a mechanical shutter, such as a MEMS shutter. In some instances, the chopper 834 may be an optical modulator or a switch. Light 864 may be transmitted through optical device 818 (step 920 of process 900). The optical device 818 may include one or more lenses, beam-directing elements, collimating or focusing elements, diffractive optics, prisms, filters, diffusers, light guides, And may be arranged in any arrangement (e.g., an RPS system or a confocal system) suitable for measuring the concentration and type of one or more materials within the sample 820 or the reference 822. [ In some instances, optical device 818 may have the same components, arrangement, and / or characteristics as optical device 816.

Light exit optics 818 may be incident on reference 822 (step 922 of process 900). The reference 822 may have the same spectral properties as the sample 820 (e.g., scatter characteristics, reflection characteristics, or both). It will be appreciated by those of ordinary skill in the art that the same spectral properties may include tolerances that cause a 15% deviation. In some instances, the criteria 822 may be a copy of the sample 820 or a "phantom" duplicate. In some instances, the absorption spectrum of the reference 822 may be the same as the absorption spectrum of the sample 820. It will be appreciated by those of ordinary skill in the art that the same absorption spectra may include tolerances that cause a 15% deviation. A portion of the light may be absorbed by the reference 822 and a portion of the light may be transmitted through the reference 822 to form the light 866. After being transmitted through the reference 822, the light 866 may be directed towards the selector 824.

The selector 824 may be any optical component that can move or select the light beam to be directed toward the detector 830. [ In some instances, the selector 824 may be coupled to the controller 840 and the controller 840 may transmit a signal (not shown) to control the movement of the selector 824. In one time period, the selector 824 may allow light 856 to be incident on the active area of the detector 830. Light 856 may comprise a set of photons and detector 830 may measure the number of photons in light 856 (step 924 of process 900). The detector 830 may generate an electrical signal 858 indicating the properties (or number of photons) of light 856 (step 926 of process 900). Signal 858 can be sent to controller 840, which can store and / or process the signal. In another time period, the selector 824 may allow the light 866 to be incident on the active area of the detector 830. Light 866 may also include a set of photons and detector 830 may measure the number of photons in light 866 (step 928 of process 900). The detector 830 may generate an electrical signal 868 indicative of the properties (or number of photons) of light 866 (step 930 of process 900). Signal 868 may be sent to controller 840, which may store and / or process the measured signal.

Detector 830 may comprise a single detector pixel or detector array. In some instances, the detector 830 may be any type of detector capable of detecting light in the SWIR. In some instances, detector 830 may be a HgCdTe, InSb or InGaAs single detector or FPA. In some examples, the detector 830 may be an SWIR detector capable of operating in an extended wavelength range of up to 2.7 [mu] m.

Controller 840 may receive both signal 858 and signal 868 at different times. Signal 858 may comprise a sample signal, and signal 868 may comprise a reference signal. In some instances, the controller 840 may divide, subtract, or scale the sample signal to a reference signal to obtain a ratio. The ratio can be converted to absorbance by using Equation 1 and an algorithm for determining the concentration of the substance of interest in sample 820 can be applied to the absorbance spectrum (step 932 of process 900). In some instances, the controller 840 may compare the reference absorbance to one or more absorbance values stored in a look-up table (LUT) or memory to determine the concentration and type of one or more materials within the sample 820. In some instances, signal 858 may differ from signal 868 by an amount of drift from light source 802, detector 830, or both. Controller 840 may divide, subtract, or scale signal 858 to signal 868 to determine the amount of drift. Although Equation 2 and the discussion above are provided in the context of absorbance, examples of the present disclosure may include, but are not limited to, any optical properties such as reflectance, refractive index, density, concentration, scattering coefficient and scattering anisotropy.

The system 800 may include all of the advantages of the system 600, while also considering changes in absorbance of the sample 820 by wavelength. While the foregoing systems illustrate one or more components such as choppers, optics, mirrors, samples, light sources, filters and detectors, those skilled in the art will appreciate that the system is not limited to the components shown in the exemplary drawings Will recognize. Those skilled in the art will also appreciate that the location and arrangement of these components is not limited to only the location and arrangement shown in the exemplary Figures.

The ideal layout or arrangement of the system will have all components shared between the optical path traveling through the sample and the optical path traveling reference, but this arrangement may not be physically possible or feasible. Examples of the present disclosure include locating one or more components that are susceptible to drifting such that the components are common or shared between two (or multiple) optical paths, and between two (or multiple optical paths) (I. E., Stable components) that are not common or difficult to drift so as not to be shared. For example, components that are susceptible to drifting may include any electronic devices or optoelectronic components. Additionally, components that are difficult to drift may include optical devices. (E.g., light source 602 and light source 802) and a detector (e.g., detector 630), as shown in both system 600 of FIG. 6 and system 800 of FIG. And detector 830) may be susceptible to drifting and thus may be shared between two optical paths (e.g., light 656 and light 666; light 856 and light 866). have. (E.g., chopper 634, chopper 636, chopper 834 and chopper 836) and optical devices (e.g., optical device 616, optical device 816, and optical Device 818) are stable and difficult to drift, and thus may be individual for each optical path.

Figure 10 illustrates an exemplary plot of absorbance measurements used to determine the concentration and type of one or more substances in accordance with the examples of this disclosure. The absorbance measurement may comprise a plurality of cycles 1076. Each cycle 1076 may include one or more dark phases 1070 and one or more measurement phases 1072. Each dark phase 1070 may include one or more steps for measuring a zero level, noise floor, stray light leakage, or a combination thereof. For example, the light source of the system may be turned off or deactivated such that the emitted light is not incident on the sampling interface or reference. The detector can take measurements to determine the amount of dark current and stray light leakage. In some instances, such measurements may be used to determine the zero level. The detector may send such measurements to the controller, which may store the measurements and / or related information in memory. The controller may use this information to determine the actual absorbance of the sample or material within the reference, or may use this information to set the zero level.

The measurement phases 1072 may be interspersed between the dark phases 1070. Measured phases 1072 may include measuring the absorbance spectrum of the sample for one hour and measuring the absorbance spectrum of the reference for another time. In some instances, any optical properties (e.g., reflectivity, refractive index, density, concentration, scattering coefficient and scattering anisotropy) can be measured instead of or in addition to the absorbance. The controller can divide or subtract or scale the absorbance spectrum of the sample by the absorbance spectrum of the reference. In some instances, the controller may compare the reference absorbance to one or more absorbance values stored in the LUT or memory to determine the concentration of the material in the sample. The measurement may be repeated many times within each measurement phase 1072 to produce a plurality of sample points 1074, and an average of sample points 1074 may be used. In some instances, the controller may compile sample points 1074 from multiple cycles 1076 when determining an average signal value. In some examples, the duration of at least one measurement phase 1072 may be based on a predetermined or fixed number of sample points 1074. [ In some examples, the number of sample points 1074 in at least one measurement phase 1072 may be less than ten. In some examples, the number of sample points 1074 in at least one measurement phase 1072 may be less than 100. [ In some instances, the duration of at least one measurement phase 1072 may be based on the stability of the reference (e.g., the time before drifting by more than 10%). For example, if the reference remains chemically stable for 60 seconds, the duration of measurement phase 1072 may also be 60 seconds. In some instances, the duration of measurement phase 1072 may be based on the stability of shared components (e.g., light source and detector). Once the measurement phase 1072 is complete, the controller may proceed to the next cycle 1076.

By more frequently correcting, both zero drift and gain drift can be considered. Additionally, unlike the procedure shown in FIG. 5, the drift can be corrected every cycle (or after a multiple number of cycles), which can prevent any significant deviation from the zero level. In addition, any variations and / or changes may be compensated before, during, or immediately after the signal begins to deflect. The accuracy of the averaged signal value can be improved by compensating for variations, drifts, and / or changes and zeroing back the zero level initially instead of after tens or hundreds of sample points 1074 have been measured. In some instances, the number of sample points 1074 taken during measurement phase 1072 may be less than the number of sample points 574 taken during measurement phase 572 (shown in FIG. 5). In some instances, the measured phase 1072 may be shorter than the measured phase 572.

In some instances, each cycle may include three measurement "measurement states ". Figure 11 shows an exemplary plot of absorbance measurements involving three measurement states with the same measurement time distribution in accordance with the examples of this disclosure. Absorbance measurements may include a plurality of cycles 1176. [ Each cycle 1176 may include three measurement states: a sample measurement state 1182, a reference measurement state 1184, and a dark measurement state 1186. The sample measurement state 1182 can be configured to measure the absorbance (or any other optical property) of a sample (e.g., sample 620 shown in Figure 6 or sample 820 shown in Figure 8) . The reference measurement state 1184 can be configured to measure the absorbance (or any other optical property) of the reference (e.g., filter 608 shown in FIG. 6 or reference 822 shown in FIG. 8) . Dark measurement state 1186 may be configured to measure dark current, stray light leakage, and / or noise. In some instances, the system may be configured to process, evaluate, and / or allocate a time distribution during the dark measurement state 1186. The system may be configured to repeat the sample measurement state 1182, the reference measurement state 1184, and the dark measurement state 1186, where none of the measurement states are shared in time. The measurement states can consist of a time duration t. In some instances, the time duration t of each measurement state may be the same. It will be appreciated by those of ordinary skill in the art that the same time duration may include tolerances that cause a 15% deviation. In this manner, the time allocated to sample measurement state 1182 may be 33% (or 1/3) of the time for cycle 1176. Similarly, each of the times assigned to the reference measurement state 1184 and the dark measurement state 1186 may be 33% (or 1/3) of the time for the cycle 1176.

The cycle time may be equally distributed in each of the three measurement states, but the signal value, noise levels and SNR for one measurement state (or measurement type) may be different from other measurement states in the same cycle. Thus, the measurement time distribution of the three measurement states may be optimal for one measurement state, but may not be optimal for the other measurement states of the cycle. Additionally, the signal values, noise levels, and SNR may vary depending on the wavelength, ambient environment, and / or measurement location of the material in the sample. As a result, the optimal measurement time distribution may be different for different wavelengths and for different positions in the sample. Additionally, configuring the measurements to include three measurement states with the same measurement time distributions may result in long measurement times with non-critical information, erroneous measurement data, low SNR, or a combination thereof.

Figure 12 shows an exemplary plot of absorbance measurements involving three measurement states with unequal measurement time distributions in accordance with the examples of this disclosure. Absorbance measurements may include a plurality of cycles, such as cycle 1276, cycle 1277, and cycle 1278. In some instances, cycle 1276 may be configured with the same time duration t ₄ as cycle 1277. Each cycle may include three measurement states: a sample measurement state 1282, a reference measurement state 1284, and a dark measurement state 1286. The sample measurement state 1282 may be configured to measure the absorbance of the sample during time t ₁ and the reference measurement state 1284 may be configured to measure the absorbance of the reference during time t ₂ and the dark measurement state 1286, It may be configured to measure the absorbance of the noise (e.g., stray light, and dark current) for the time t _3. In some instances, the sample signal may be weak or may have low intensity (e.g., less than 20% of the intensity of the reference signal), as shown in cycle 1276. The system may allocate the time for the sample measurement state 1282 of the cycle 1276 to be greater than the time for other measurement states. For example, the intensity of the sample signal may be 4.3% of the intensity of the reference signal and time t ₄ can be distributed in time of t _1, t ₂ and t ₃ containing 65%, 30% and 5%, respectively. In some instances, time t ₁ may be 50% or more of the time for cycle 1276.

In some instances, the sample signal may be stronger or stronger than the reference signal, as shown in cycle 1277. The sample measurement state 1282 may be composed of time t ₁₁ , the reference measurement state 1284 may be composed of time t ₁₂ , and the dark measurement state 1286 may be composed of time t ₁₃ . The system may allocate the time for the reference measurement state 1284 of the cycle 1277 to be greater than the time for other measurement states. For example, the intensity of the sample signal may be 85% of the intensity of the reference signal , And time t ₄ may be distributed as times t ₁₁ , t _12, and t ₁₃ , including 20%, 60%, and 5%, respectively. In some instances, time t ₁₂ may be at least 50% of the time for cycle 1277.

As shown in the figure, the measurement time per cycle can be distributed based on the signal values and the noise levels, and this distribution can be changed dynamically. For example, if the noise levels are low, the system can be configured to take less time in the dark measurement state. In some instances, each cycle time may be different and / or may be dynamically changed. In some instances, the measurement time distribution may be based on the operating wavelength. For example, the operating wavelengths may include one or more wavelengths of lower importance (e.g., due to a lower probability of absorbance by the material of interest), and thus the system may measure one or more wavelengths of lower importance It can be configured to take less time. In this way, the total measurement time can be reduced, long measurement times with non-critical information can be avoided, and the measurement accuracy can be improved.

In some instances, the measurement time distribution may be based on a predetermined or targeted SNR. For example, if the signal values are weak, the system can be configured to take more time in the sample measurement state or the reference measurement state, so that accurate signal values can be measured and non-critical measurement information can be avoided. In some instances, the time taken to measure the noise can be dynamically changed based on the SNR, and the remaining time is such that half of the remaining time is spent measuring the sample and the other half of the time remaining is used to measure the reference Can be distributed.

In some instances, the measurement time distribution may be based on the position measured at the sample or associated detector pixel. Each detector pixel may be associated with a location in the sample or a corresponding optical path. In some instances, different optical paths may be incident on different locations within the sample. In some instances, the sample signal values of the detector pixels may be different. The different sample signal values may be obtained from any number of sources, e.g., from different positions in the sample, from different ones, from system components (e.g., light sources, waveguides, modulators, optics, detectors) (E.g., operating temperature or environmental changes in components) in the operating conditions. Thus, the system can be composed of at least two detector pixels having different measurement time distribution values.

The system can be configured to dynamically change the actual measurement time distribution because the optimal measurement time distribution can vary depending on the signal values, noise levels, wavelength and measurement location in the sample, It is possible to derive a reduced overall measurement time without compromising accuracy. In some instances, the system may include a LUT that may include actual measurement time distribution values and associations to the operating wavelength and detector pixels. In some instances, the LUT may store various configurations in which the configuration may be selected based on the calibration-phase measurements. The system may be optimized and tuned based on operating conditions for the measurements and / or the application of the system.

Figure 13 illustrates an exemplary process flow for dynamically varying the measurement time distribution in accordance with the examples of this disclosure. Process 1300 can include measuring signal values, noise levels, or both, for a detector pixel at a given wavelength (step 1302). In some instances, the measurement may be a coarse measurement performed for a predetermined time. The measurements may be repeated for other detector pixels included in the system (step 1304 and step 1306). Based on the measured signal values and noise levels, the controller or processor included in the system may use the LUT to determine the time and percentages for each of the plurality of measurement states (step 1308). In some instances, the LUT may include targeting or a predetermined SNR, which may be used to determine times and percentages for measurement states. Using the determined times and percentages, the system can dynamically change the measurement time distribution (step 1310). In some instances, the system may include logic that provides feedback regarding the overall measurement time, measurement accuracy, and actual SNR, and the system may rewrite or update the LUT based on any deviation from the targeted values. The measurements may be repeated for other wavelengths of interest (steps 1312 and 1314). If all detector pixels of interest and wavelengths of interest are measured, the system may repeat the measurements (step 1316).

In some instances, different measurement states can be measured simultaneously. Figure 14 illustrates a portion of an exemplary system capable of measuring the concentration and type of one or more materials in a sample and measuring different measurement states simultaneously in accordance with the examples of this disclosure. The system 1400 includes a system 100 (shown in FIG. 1), a system 300 (shown in FIG. 3), a system 600 (shown in FIG. 6), and a system 800 Such as a light source 1402, a controller 1440, a filter 1406, a filter 1407, a beam splitter 1410, and a plurality of components having one or more of the attributes discussed above in the context of the present invention. A mirror 1412, a chopper 1434, a chopper 1436, an optical device 1416, an optical device 1417 and an optical device 1418. The system 1400 may further include a plurality of detectors, e.g., a detector 1430, a detector 1431, and a detector 1432. The detector 1430 may be configured to measure a reference signal during a reference measurement state (e.g., a reference measurement state 1184 or a reference measurement state 1284) Lt; RTI ID = 0.0 > 1468 < / RTI > Detector 1431 may be configured to measure noise (e.g., dark current) during a dark measurement state (e.g., dark measurement state 1186 or dark measurement state 1286) Lt; RTI ID = 0.0 > 1478 < / RTI > The detector 1432 may be configured to measure the sample signal during a sample measurement state (e.g., a sample measurement state 1182 or a sample measurement state 1282), and the properties of the light 1456 through the sample 1420 Lt; RTI ID = 0.0 > 1458 < / RTI > In this way, a plurality of detectors can be used to simultaneously measure the sample signal, the reference signal, and the noise signal. During one cycle, the system may generate a plurality of reference measurements, and at least one detector pixel may be always measuring a signal (e.g., a sample signal, a reference signal, or a noise signal).

Figure 15 illustrates an exemplary plot of measurement states for a system that can measure different measurement states simultaneously according to the examples of this disclosure. The system can include three detectors, i.e., detector 1, detector 2 and detector 3, and includes three measurement states: a sample measurement state 1582, a reference measurement state 1584 and a dark measurement state 1586 ). During time t ₁ , detector 1 may be configured to measure the noise signal in the dark measurement state 1586. At the same time, detector 2 may be configured to measure a reference signal in a reference measurement state 1584 and detector 3 may be configured to measure a sample signal in a sample measurement state 1582. In other time t _2, the measurement conditions for each of the detectors may be varied. Detector 1 may be configured to measure a sample signal in a sample measurement state 1582 and detector 2 may be configured to measure a noise signal in a dark measurement state 1586 and detector 3 may be configured to measure a noise signal in a reference measurement state 1584 May be configured to measure a reference signal. As shown in the figures, each detector (e.g., detector 1, detector 2, and detector 3) can always measure one of three signals values. That is, the measurement states can be measured simultaneously over different detectors and continuously at each detector. In some instances, the system may include a tunable mirror configured to direct or redirect light to different detectors. In some examples, the tunable mirror may comprise a plurality of data light processing (DLP) mirrors. In some instances, light may be redirected using one or more beam splitters.

In some instances, the system may comprise a plurality of microelectromechanical systems (MEMS) components. 16 illustrates a cross-sectional view of a portion of an exemplary system that includes a plurality of MEMS components and can measure different measurement states simultaneously according to examples of the present disclosure. System 1600 includes a plurality of detector pixels, e.g., detector pixel 1633 and detector pixel 1635, and a plurality of MEMS components, e.g., MEMS component 1623, included in detector array 1630. [ And a MEMS component 1625. Each detector pixel may be coupled to a MEMS component. For example, a detector pixel 1633 may be coupled to a MEMS component 1623, and a detector pixel 1635 may be coupled to a MEMS component 1625. Light 1656 may be light reflected from the sample and MEMS component 1623 may be angled or oriented such that light 1656 is incident on detector pixel 1633. Additionally, light 1666, which may be reflected from the reference, may be blocked by the MEMS component 1623. The MEMS component 1625 is positioned such that the light 1666 is incident on the detector pixel 1637 and the light 1656 (i.e., the light reflected from the sample) is blocked to prevent it from reaching the detector pixel 1635 ≪ / RTI > In some instances, a MEMS component can vary orientations for different times, measuring light from a sample at one time, and then measuring light from a reference at another time. In some instances, one or more adjacent detector pixels in the detector array 1630 or adjacent sets of detector pixels may have MEMS components with different orientations.

In some instances, noise levels may result in variations that can be correlated in time. Figure 17 shows an exemplary plot of absorbance measurements with noise variations in accordance with the examples of this disclosure. The measurement may include a plurality of sample points, e.g., a sample point 1774 and a sample point 1775. Sample point 1774 may be included in sample measurement state 1782 and sample point 1775 may be included in reference measurement state 1784. [ The noise contained in the sample point 1774 may be different from the noise contained in the sample point 1775, which may result in time correlated noise in the sample signal and the reference signal. The correlated noise of the sample and reference signals can lead to erroneous measurements.

Noise common to both the sample signal and the reference signal may be referred to as common mode noise. In some instances, the common mode noise may result from the light sources included in the system, as well as from other components of the system that may be used to route, attenuate, and / or shape the light beam emitted from the light sources. The light sources may include multiple types of noise, e.g., long-term drift and short-term noise. The correlated canceled noise mentioned earlier may be a short term noise which may be high frequency noise.

Figure 18 illustrates an exemplary system, and Figure 19 illustrates an exemplary process flow for measuring the concentration and type of one or more materials in a sample comprising a high frequency detector in accordance with the examples of this disclosure. The system 1800 includes a system 100 (shown in FIG. 1), a system 300 (shown in FIG. 3), a system 600 (shown in FIG. 5), a system 800 For example, a light source 1802, a controller 1840, a filter 1806, and a light source 1806 having one or more of the attributes discussed above in the context of the system 1400 (shown in FIG. 14) A beam splitter 1810, a mirror 1812, a chopper 1834, a chopper 1836, an optical device 1816, an optical device 1818, a detector 1830 and a detector 1832. The system 1800 may further include a beam splitter 1811 and a detector 1833. The beam splitter 1811 may be an optical component configured to separate the incident light into a plurality of light beams. One or more of these hardware components may operate under software control of the controller 1840 to change the measurement cycles and states described herein. One or more of these hardware components and controllers may be referred to herein as logic.

Light source 1802 may be directed towards filter 1806 and signal 1804 may cause light source 1802 to emit light 1850 (step 1902 of process 1900). Light 1850 may comprise a plurality of wavelengths and may be transmitted through filter 1806 and form light 1852 that includes one or more discrete wavelengths (step 1900 of process 1904). Light 1852 may be directed toward beam splitter 1811 and beam splitter 1811 may split light 1852 into two light paths, i.e., light 1853 and light 1855 (Step 1906 of process 1900).

Light 1853 can be directed toward beam splitter 1810 and beam splitter 1811 can split light 1853 into two light beams, i.e., light 1854 and light 1864 Step 1908 of process 1900). Light 1854 may be transmitted through chopper 1834 and optics 1816. Light 1854 may be incident on sample 1820 and one or more materials within sample 1820 may absorb at least a portion of light 1854. [ Light that is transmitted through or reflected from the sample 1820 may be referred to as light 1856. [ Detector 1832 can detect light 1856 and generate signal 1858 indicative of the properties of light 1856 (step 1910 of process 1900). In addition, light 1864 may be directed or redirected by mirror 1812 and transmitted through chopper 1836 and optics 1818. [ Light 1864 may be incident on reference 1822 and some may be transmitted through reference 1822 as light 1866 or may be reflected therefrom. Detector 1830 can detect light 1866 and generate signal 1868 indicative of the properties of light 1866 (step 1912 of process 1900). In some instances, the detector 1830 and the detector 1832 may measure the reference signal and the sample signal at the same time or simultaneously, respectively. In some instances, detector 1830 and detector 1832 may measure the reference signal and the sample signal at different times. In some instances, the system 1800 may be configured such that a single detector measures both the sample signal and the reference signal.

The detector 1833 may be configured to measure the light 1853 and generate a signal 1888 indicative of the properties of the light 1855 (step 1914 of process 1900). In some instances, the detector 1833 may be a high frequency detector that may be AC coupled to measure high frequency noise. Controller 1840 may receive signal 1888 and calculate common mode noise for each of the signals (e.g., sample signal and reference signal) in time (step 1916 of process 1900) ). Based on the calculated common mode noise, the controller 1840 may generate one or more normalization factors for each of the signals (step 1918 of process 1900). In some instances, the normalization factors may be generated based on matching the noise strength of the signal 1888 with the signal 1858 and / or the signal 1868. In some examples, matching the noise strength of the signal 1888 with the signal 1858 and / or the signal 1868 may include reducing differences in the intensity values of the signals. The sample and reference signals may be corrected or scaled based on the normalization factors or the scaling scheme (step 1920 of process 1900). In some instances, normalization factors or scaling schemes may be based on standard deviation. The corrected or scaled signals can then be used to determine the concentration and type of one or more materials in the sample (step 1922 of process 1900).

By detecting the high frequency noise included in the light 1852 with the detector 1833, the sample signal noise can be reduced and the SNR can be improved. In some instances, the detector 1833 may be configured with different gains from the detector 1830, the detector 1832, or both. In some instances, beam splitter 1811 can separate light 1852 such that light 1853 and light 1855 have different intensities.

One or more of the foregoing functions may be performed, for example, by firmware stored in memory and executed by a processor or controller. The firmware may also be used by or in connection with an instruction execution system, device, or device, such as a computer-based system, processor-embedded system, or other system capable of fetching instructions from an instruction execution system, / RTI > may be stored and / or transmitted within any non-volatile computer readable storage medium for < / RTI > In connection with the present specification, "non-volatile computer readable storage medium" refers to any medium (other than a signal) that may contain or store a program for use by or in connection with an instruction execution system, . Non-volatile computer readable storage media include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or devices, portable computer diskettes (magnetic), random access memory A removable optical disk such as a CD-ROM, a CD-RW, a DVD, a DVD-R or a DVD-RW, or a compact flash card, a secure digital card , A USB memory device, a flash memory such as a memory stick, and the like. In the context of this document, "transmission medium" may be any medium capable of transmitting, propagating, or transmitting a program for use by or in connection with an instruction execution system, apparatus, or device. The transfer-readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, or infrared type wired or wireless propagation media.

As discussed above, examples of the present disclosure may include measuring the concentration of a substance in a sample at a sampling interface. In some instances, the sample may include at least a portion of a user, where additional information may be used to improve delivery of measured information, analysis, or any other content that may be of interest to users. In some instances, the measured information, analysis, or other content includes personal information, e.g., information that can uniquely identify the user (e.g., may be used to contact the user or to locate the user) can do. In some instances, the personal information may include geographic information, demographic information, telephone numbers, email addresses, mailing addresses, home addresses, or other identifying information. The use of such personal information may be used for the benefit of the user. For example, personal information may be used to convey measured information, analysis, or other content to a user. The use of personal information may include, but is not limited to, enabling the proper and controlled delivery of the measured information.

The present disclosure also contemplates that entities capable of measuring, collecting, analyzing, disclosing, transmitting and / or storing personal information will comply with well-established privacy policies and / or practices. These privacy policies and / or practices generally can be perceived, implemented, and used consistently to meet (or exceed) industry or government requirements for confidential and secure personal information. For example, personal information should be collected for legitimate and valid purposes (eg, conveying measured information to users) and should not be shared (eg, sold) outside of those purposes. In addition, the collected personal information should only occur after receiving the informed consent of the user (s). To comply with privacy policies and / or practices, entities must take any steps necessary to safeguard and secure external access to personal information. In some instances, the entities may receive third party evaluation (s) to prove that the entities are well-configured and conform to generally recognized privacy policies and / or practices.

In some instances, the user (s) may selectively block or restrict access to and / or use of personal information. The measurement system may include one or more hardware components and / or one or more software applications to allow the user (s) to selectively block or restrict access and / or use to personal information. For example, the measurement system may be configured to allow users to "opt in" or "opt out" ad delivery services when collecting personal information during registration. In some instances, the user may select which information to provide (e.g., geographic location) and which information to exclude (e.g., phone number).

Examples of the present disclosure may include systems and methods for measuring the concentration of a substance by the use of a user ' s personal information, but the examples of this disclosure also disclose that one or more functions and actions It can be possible. Lack of all or part of the personal information may not render the systems and methods inoperable. In some instances, the content may be delivered to the user and / or selected based on non-user specific individuals (e.g., publicly available) information.

A system for determining the concentration and type of material in a sample at a sampling interface is disclosed. In some examples, the system comprises: one or more detector pixels comprising a first detector pixel, the one or more detector pixels being configured to operate in a plurality of cycles, each cycle comprising a plurality of measurement states, The states include a first measurement state configured to measure one or more optical properties of a material during a first time period, a second measurement state configured to measure one or more optical properties of the reference during a second time period, A third measurement state configured to measure noise during the first measurement state; And logic to dynamically change one or more aspects of the plurality of cycles, wherein the one or more aspects comprise a duration of each time period. Additionally or alternatively, in some examples, the one or more detector pixels further comprise a second detector pixel, wherein at the same time the first detector pixel is configured in a first measurement state and the second detector pixel is in a second measurement state . Additionally or alternatively, in some examples, the one or more detector pixels further comprise a third detector pixel, and at the same time the third detector pixel is configured in a third measurement state. Additionally or alternatively, in some examples, the system further comprises a plurality of mirrors, each mirror associated with a detector pixel contained in a plurality of detector pixels, configured with an orientation such that the first light is reflected or blocked And is further configured to provide an associated detector pixel access to the second light different from the first light. Additionally or alternatively, in some examples, the system further comprises a detector pixel comprised of a first measurement state, a second measurement state and a third measurement state, wherein the first, second and third measurement states are continuous, The determination of the concentration and type of material is based on the first, second and third measurement states.

A method for determining the concentration and type of material in a sample at a sampling interface during a plurality of cycles including a first cycle and a second cycle is disclosed. In some examples, the method includes measuring one or more optical properties of a material during a first time period during a first cycle; Measuring one or more optical properties of the reference during a second time period; Measuring noise during a third time period; And dynamically changing at least one duration of the first time period, the second time period and the third time period during the second cycle. Additionally or alternatively, in some instances, at least two of the first time period, the second time period and the third time period in the first cycle are different. Additionally or alternatively, in some instances, measuring one or more optical properties of the material includes obtaining a first signal value, wherein measuring one or more optical properties of the reference acquires a second signal value The method comprising: comparing a first signal value to a second signal value; And setting a first time period greater than a second time period when the first signal value is less than the second signal value. Additionally or alternatively, in some instances, the first time period is set to greater than 50% of the time period for the first cycle. Additionally or alternatively, in some instances, measuring one or more optical properties of the material includes obtaining a first signal value, wherein measuring one or more optical properties of the reference acquires a second signal value The method comprising: comparing a first signal value to a second signal value; And setting the first time period to be smaller than the second time period when the first signal value is larger than the second signal value. Additionally or alternatively, in some instances, the second time period is set to be greater than 50% of the time period for the first cycle. Additionally or alternatively, in some instances, the first cycle comprises a first operating wavelength, the second cycle comprises a second operating wavelength, the first operating wavelength is different from the second operating wavelength, Has at least one of a first time period, a second time period and a third time period different from the second cycle. Additionally or alternatively, in some instances, the first time period is the same as the second time period in the first cycle. Additionally or alternatively, in some examples, each cycle included in a plurality of cycles is associated with a detector pixel contained in a plurality of detector pixels, the method further comprising retrieving one or more entries from the lookup table, Wherein the entries include at least one of an association between a first time period, a second time period and a third time period, and an operating wavelength and a detector pixel; And setting at least one of a first time period, a second time period and a third time period based on the one or more entries. Additionally or alternatively, in some instances, at least one of the first time period, the second time period and the third time period is different for at least two detector pixels included in the plurality of detector pixels. Additionally or alternatively, in some examples, the method includes determining an operating wavelength and an attribute associated with the detector pixel, wherein the attribute is at least one of a measurement time, a measurement accuracy, and a signal-to-noise ratio (SNR); Comparing the attribute with one or more entries from a look-up table; And updating one or more entries from the look-up table based on the comparison. Additionally or alternatively, in some examples, the plurality of cycles further comprises a third cycle, wherein the first time period for the first cycle is a second time period for the second cycle and the second time period for the third cycle 3 hours period.

A system for determining the concentration and type of material in a sample at a sampling interface is disclosed. In some examples, the system is configured to emit first light and second light-the first light is incident on the sampling interface, the second light is incident on the reference, and the first light and the second light are noise ≪ / RTI > A first detector configured to measure incident light, the incident light being at least one of a first light and a second light and being configured to generate a first signal indicative of incident light; A second detector configured to measure a noise component included in a range of frequencies and configured to generate a second signal indicative of the measured noise component; And logic that is capable of scaling the second signal and using the scaled second signal to compensate for the first signal. Additionally or alternatively, in some instances, the gain of the first detector is different from the gain of the second detector. Additionally or alternatively, in some instances, the intensity of the first light is different from the intensity of the second light.

Although the disclosed examples have been fully described with reference to the accompanying drawings, it should be noted that various changes and modifications will be apparent to those skilled in the art to which the invention pertains. Such changes and modifications are to be understood as being included within the scope of the disclosed examples as defined by the appended claims.

Claims (20)

A system for determining the concentration and type of material in a sample at a sampling interface,
One or more detector pixels comprising a first detector pixel, wherein the one or more detector pixels are configured to operate in a plurality of cycles, each cycle comprising a plurality of measurement states,
A first measurement state configured to measure one or more optical properties of the material in the sample during a first time period,
A second measurement state configured to measure one or more optical properties of the reference during a second time period, and
A third measurement state configured to measure noise during a third time period; And
And logic to dynamically change one or more aspects of the plurality of cycles, wherein the one or more aspects comprise a duration of each time period. 2. The method of claim 1, wherein the one or more detector pixels further comprise a second detector pixel, the first detector pixel at the same time being configured in the first measurement state, ≪ / RTI > 3. The system of claim 2, wherein the at least one detector pixel further comprises a third detector pixel, and at the same time the third detector pixel is configured in the third measurement state. 3. The method of claim 2,
Wherein each of the plurality of detector pixels comprises a plurality of mirrors, each mirror being associated with a detector pixel included in the plurality of detector pixels, the first mirror being configured in an orientation such that the first light is reflected or blocked, To the associated detector pixel. ≪ Desc / Clms Page number 12 > The method according to claim 1,
Wherein the first, second and third measurement states are continuous, and wherein the determination of the concentration and type of the substance, wherein the first, second and third measurement states comprise a first detector state, Is based on the first, second and third measurement states. CLAIMS What is claimed is: 1. A method for determining the concentration and type of material in a sample at a sampling interface during a plurality of cycles comprising a first cycle and a second cycle,
During the first cycle:
Measuring one or more optical properties of the material at the sampling interface during a first time period;
Measuring one or more optical properties of the reference during a second time period;
Measuring noise during a third time period; And
And dynamically changing at least one duration of the first time period, the second time period and the third time period during the second cycle. 7. The method of claim 6, wherein at least two of the first time period, the second time period and the third time period in the first cycle are different. 7. The method of claim 6, wherein measuring one or more optical properties of the material comprises obtaining a first signal value, wherein measuring one or more optical properties of the reference comprises obtaining a second signal value The method comprising:
Comparing the first signal value with the second signal value; And
Further comprising setting the first time period to be greater than the second time period if the first signal value is less than the second signal value. 9. The method of claim 8, wherein the duration of the first time period is set to be greater than 50% of the duration of the first cycle. 7. The method of claim 6 wherein measuring one or more optical properties of the material comprises obtaining a first signal value, wherein measuring one or more optical properties of the reference comprises obtaining a second signal value The method comprising:
Comparing the first signal value with the second signal value; And
Setting the first time period to be less than the second time period if the first signal value is greater than the second signal value. 11. The method of claim 10, wherein the duration of the second time period is set to be greater than 50% of the duration of the first cycle. 7. The method of claim 6, wherein the first cycle comprises a first operating wavelength, the second cycle comprises a second operating wavelength, the first operating wavelength is different from the second operating wavelength, Wherein the cycle has at least one of the first time period, the second time period and the third time period different from the second cycle. 7. The method of claim 6, wherein the duration of the first time period is equal to the duration of the second time period in the first cycle. 7. The method of claim 6, wherein each cycle included in the plurality of cycles is associated with a detector pixel included in a plurality of detector pixels,
Retrieving one or more entries from a look-up table, the one or more entries including at least one of an association between the first time period, the second time period and the third time period, and an operating wavelength and the detector pixel, ; And
Setting at least one of the first time period, the second time period and the third time period based on the one or more entries. 15. The method of claim 14, wherein at least one of the first time period, the second time period and the third time period is different for at least two detector pixels included in the plurality of detector pixels. 15. The method of claim 14,
Determining an operating wavelength and an attribute associated with the detector pixel, the attribute being at least one of a measurement time, a measurement accuracy, and a signal-to-noise ratio (SNR);
Comparing the attribute to the one or more entries from the lookup table; And
And updating the one or more entries from the look-up table based on the comparison. 7. The method of claim 6, wherein the plurality of cycles further comprise a third cycle, and wherein the duration of the first time period for the first cycle is greater than the duration of the second time period for the second cycle And a duration of the third time period for the third cycle. A system for determining the concentration and type of material within a sample site comprising a sampling interface,
A light source configured to emit first light and second light, the first light incident on the sample interface, the second light incident on a reference, the first light and the second light having a noise component ≪ / RTI >
A first detector configured to measure incident light, the incident light being at least one of the first light and the second light, and configured to generate a first signal indicative of the incident light;
A second detector configured to measure the noise component included in a range of frequencies and to generate a second signal indicative of the measured noise component; And
And logic that is capable of scaling the second signal and using the scaled second signal to compensate for the first signal. 19. The system of claim 18, wherein the gain of the first detector is different from the gain of the second detector. 20. The system of claim 19, wherein the intensity of the first light is different from the intensity of the second light.

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